Sheet feeding apparatus

ABSTRACT

Machine for feeding single sheets from a pile or stack. The machine performs a two step operation. For the first step it has piston and abutment means for exerting a compressive force on the stack and later releasing this force. A pusher engages an edge of the top sheet with resilient pushing pressure, while the compressive force is in effect. Thus, the pusher does not immediately shift the top sheet but as the compressive force is being released, this reduces the friction between the top abutment, the top sheet and the next sheet. As a result the pusher then shifts the top sheet, and it is shifted in flat condition and accurately through a nip or slot which accepts only this sheet and prevents simultaneous feeding out of several sheets. The second step is then performed by feed rollers or the like, which engage and if necessary clamp the edge of the top sheet opposite the pusher and move the same and the entire top sheet from the pile, preferably in a direction transverse that of the pusher.

United States Patent [191 Gronlund-Nielsen SHEET FEEDING APPARATUS Axel Gronlund-Nielsen, Ellekrogen, 2950 Vedback, Denmark [22] Filed: June 14, 1972 [21] Appl. No; 262,882

Related US. Application Data [63] Continuation-impart of Ser. No. 47,492, June 16,

1970, abandoned.

[ 76] Inventor:

[30] Foreign Application Priority Data June 16, 1969 Denmark 3214/69 [52] U.S. Cl. 271/10, 271/18 R, 271/188 [51] Int. Cl. B65h 3/24 [58] Field of Search 271/18 R, 10, 16, 42, 19, 271/21, 22,128, 24, 25, 135, 160;214/8.5 A, 8.5 F

[56] References Cited UNITED STATES PATENTS 3,067,885 12/1962 Kohler 271/130 3,160,411 12/1964 Fiehl 27l/10X 1,025,282 5/1912 Lev 271/22 3,195,740 7/1965 Lange et a1. 271/42 X 3,008,709 11/1961 Buslik 271/10 2,935,315 5/1960 Socke 271/105 X Primary Examiner-Richard E. Aegerter Assistant Examiner-Bruce H. Stoner, Jr.

Attorney, Agent, or Firm-Albert C. Nolte, Jr.; Edward B. Hunter; Charles B. Hamburg [57] ABSTRACT Machine for feeding single sheets from a pile or stack.

The machine performs a two step operation. For the first step it has piston and abutment means for exerting a compressive force on the stack and later releasing this force. A pusher engages an edge of the top sheet with resilient pushing pressure, while the compressive force is in effect. Thus, the pusher does not immediately shift the top sheet but as the compressive force is being released, this reduces the friction between the top abutment, the top sheet and the next sheet. As a result the pusher then shifts the top sheet, and it is shifted in flat condition and accurately through a nip or slot which accepts only this sheet and prevents simultaneous feeding out of several sheets. The second step is then performed by feed rollers or the like, which engage and if necessary clamp the edge of the top sheet opposite the pusher and move the same and the entire top sheet from the pile, preferably in a direction transverse that of the pusher.

MTENTEDAPRN I974 3,8061 13 SHEET 1 [IF 2 ATTORNEY FATEHTEIMPR 1974 3.8061 13 SHEET 2 BF 2 ATTORNEY BACKGROUND AND NATURE OF'THE INVENTION The invention relates to apparatus for feeding any kind of sheet material from a pile and particularly feeding the sheets one by one and without accidental entrainment of one sheet by another. In prior apparatus, operating on the top sheet of the stack supply of sheets, it also happened that underlying sheets were fully or partly entrained by the top sheet to be moved from the pile. Such difficulty arose, for instance when the sheets in the pile were greased to protect them from corrosion or when their edges were burred or when the sheets were very thin and atmospheric pressure held them together. Evidently it was desirable to separate the sheets, for example by moving them through a narrow slot, but this was not always possible as the sheets then tended to bulk and to lose alignment with the slot.

The new apparatus, by contrast, allows feeding out of a single sheet, from the top of the pile, without the aforementioned difficulties.

This is achieved by a new combination of devices including means for subjecting the pile to a temporary compressing force; pusher means resiliently engageable with an edge of the top sheet; means to release the compressive force whereupon the resilient engagement of the pusher slightly shifts the top sheet while it still is guided between the underlying sheet and the pile compressing means; means for restraining the underlying sheet from being shifted with the top sheet; and means for removing the shifted top sheet from the pile.

This combination has the effect that the top sheet remains plane and can be shifted accurately, relative to the means for restraining the underlying sheet.

DRAWINGS FIG. 1 is a plan view of apparatus according to the invention;

FIG. 2 is an elevation of the same apparatus seen from the front thereof; and

FIG. 3, is a schematic sectional view of a preferred form of a sheet pusher element.

As shown in FIGS. 1 and 2, table 1 supports a pile 2 of sheets (which can be of various dimensions and materials and for example may include narrow strips and various other units). The table can be raised and lowered by hydraulic cylinder 3, which for the sake of simplicity is shown in the drawing as placed under the table and acting directly on the same.

Over the pile 2 and at the forward end of the same (as seen in the direction 14 of the feeding out of sheets) there is provided a top abutment, formed by a cross bar 4 which in the embodiment shown is fixed. It has a flat, horizontal undersurface so that, when table 1 raises pile 2 the top sheet is subjected to compression all along the said undersurface.

The cross bar 4 carries at one end thereof a slide or pusher 5 and power means 6 for sliding it in a direction along the cross bar and across the feeding direction 14. The aggregate 5, 6 may be secured to the cross bar 4 releasably so that it can be installed in different positions to accommodate different widths of pile 2. Preferably, for reasons to be noted presently, power means 6 is a pneumatic cylinder and piston unit. The exact construction of this unit and of cylinder 3, is. unimportant for the invention, as is the construction of the hydraulic and pneumatic piping, valving, and force generators, which therefore are not shown.

At the opposite end of cross bar 4 two stops 7 and 8 are provided, one above the other, to define between them a horizontal slot 9, desirably of adjustable width. The upper stop 8 has its undersurface aligned with that of the cross bar while the lower stop desirably has its upper surface slightly below the underside of the top sheet but above the underside of the next following sheet.

The apparatus described up to this point works in the following way.

Table l with pile 2 thereon is raised by activating hydraulic cylinder 3 and the pile is thereby pressed hard against the flat underside of cross bar 4. Pneumatic cylinder 6 then is activated to cause pusher 5 to engage the edge of the top sheet in pile 2. Initially, this engagement does not cause motion of the top sheet but causes the building up of resilient air pressure in the pneumatic cylinder unit 6. The pressure in hydraulic cylinder 3 is then released. As the compression of the pile is being released thereby the resilient pressure of pusher motor 6 becomes sufficient to shift the top sheet a short distance across the pile, while the top sheet still is being frictionally guided between the underside of cross bar 4 and the top surface'of the next following sheet. Thus, the slight lateral shifting or the top sheet causes this sheet to accurately pass through the slot 9, while the next following sheet is prevented by stop 7 from moving along with the top sheet.

These several operative steps may be seen as a first phase of the operation of the new apparatus. For completion of the feeding out of the top sheet there is provided additional equipment, illustrated in form of sheet rollers 10 and 11 disposed in the vicinity of cross bar 4, on the side opposite members 7, 8. These rollers are vertically spaced from one another by a nip or distance which can be somewhat greater than slot 9 of the stop unit. A hydraulic cylinder unit 13 is shown for pressing the upper roller 11 against the sheet and thereby.

clamping the sheet between rollers 10 and 11, which can then be rotated by well known means, not shown, to move the sheet in the direction of arrow 14.

If lateral shifting of a sheet takes place at one end as illustrated and the rearward portions of the sheet are restrained for example by stops 15, the feeding out takes place at a small angle to the original edge of the sheet, as will be obvious by comparison of sheet positions 2 and 2'. Of course position 2' can be controlled by suitable installation of the entire machine and various other forms of control of the feed direction can obviously be used.

A preferred form of the transverse pusher is shown schematically in FIG. 3. It comprises an arm 20, pivoted at 21 to the pneumatic slider, not shown in this figure. Undersurface 22 of this arm is provided at its forward end as seen in the direction of lateral displacement of the slider or pusher, and this undersurface normally rests on sheet 23. Spring 24 may be provided to press arm 20 against the sheet.

For proper engagement with a side edge of sheet 23, there is provided a step of a height a little less than the thickness of the sheet. This step is provided by a block 25 advantageously similar to a planing blade. It is downwardly adjustable by screw 26 and when adjusted, can be fixed in arm 20 by screw 27.

Advantageously, block 25 has a convergent edge facing the edge of the sheet to be shifted, and has a flat underside slidable in contact with the next lower sheet, as is suggested by the drawing. This construction insures reliable separating of sheets, particularly when their thickness is less than one thirty-second inch. The sharp forward edge of block 25 may be seen as acting on the edge of sheet 23 below the meridian plane of the latter, thus producing a bending moment, which causes the sheet adjacent this edge to bend upward to a minute extent, as allowed by surface 22 being spaced from block 25. This action reduces forcesof cohesion between the sheets such as the forces due to atmospheric pressure or to oil or grease on the sheet surfaces. The shifting and removal of the single top sheet is facilitated thereby.

In some cases it may be desirable to insert the sharp edge of the pusher below the edge of the sheet to be shifted and to lift the latter edge. This is further promoted by providing a recess 28 between undersurface 22 and the edge of block 25, as shown.

It will be understood that various expedients can be used to adapt the pusher toindividual cases. Replaceable arms, generally like arm 20, can have differently adjusted blocks 25, to fit different thicknesses of sheets. They can be attached to the pneumatic pusher unit by various devices, including for example universal joints, so as to accurately follow the top surface of the sheet to be shifted even if this surface is not exactly horizontal.

Referring once more to FIGS. 1 and 2, when the top sheet has been shifted laterally and then engaged for feeding out, pneumatic cylinder 6 can return pusher to its starting position. It is then possible, for example by automatic control means not shown to activate hydraulic cylinder 13 and thereby to press rollers 10 and 11 against the sheet, while making ready to activate pneumatic cylinder 6 of pusher 5 for transverse shifting of the next following sheet.

The new machine is able to feed individual sheets from pile 2 even when these sheets adhere to one another quite strongly. A slight lateral shift from position 2 to 2' suffices to make sure that the ultimate feeding equipment 10, ll safely engages a single sheet, fed through slot 9, under the guidance of abutment 4 and the underlying sheet. Evidently the construction is simple, yet it achieves a high degree of security'that the sheets are fed from the pile only one by one. The time needed for the first step of the new operation application of pressure and friction effect and a very slight lateral shifting of the top sheet as these effects are being released is minimal, and greatly improved feeding out action, in direction 14, is achieved thereby. The operation can be rapid and can be made to coincide fully with the requirement of the machine to which the sheets are to be delivered.

What is claimed is:

1. A feeding apparatus for individual feeding of sheet material from a pile in a first, feeding direction, comprising supporting means for the pile, a top abutment placed over the pile, power means for relative reciprocal movement of said supporting means and top abutment means against and away from each other to exert temporarily, a compressive force on and to release the same from the pile in the vertical direction only, pusher means for engaging an edge of the top sheet in the pile, means guiding said pusher means in a second direction parallel with the plane of the sheets and lateral of said feeding direction, means for biasing the pusher means against the edge of the top sheet, while said compressive force is exerted on the pile and during release therefrom, for exerting thereon a resilient pressure which is insufficient to overcome the friction caused by said compressive force on the pile but sufficient to laterally displace said top sheet when said compressive force on the pile is being released, a feeding device arranged at the side of the pile in level with said top abutment means opposite the pusher means and having means for.receiving and gripping said top sheet and for feeding it in the feeding direction after its displacement by the pusher means, and means opposite the pusher means in level with said top sheet for passage of the opposite edge of the top sheet during said displacing of the top sheet and for stopping movement of the sheet immediately below the top sheet.

2. A feeding apparatus as described in claim 1 wherein said pusher means includes a pusher arm having a surface to rest on the top of the pile, and having behind said surface a step slightly lower than the thickness of a sheet in the pile and a recess between said sur face and said step for temporarily receiving the edge of the top sheet as it is lifted by said step. Y

3. A feeding apparatus as claimed in claim 1 including stop means closely adjacent the edge of top sheet on the side opposite said pusher and downstream thereof relative to said first, feeding direction for limiting lateral movement of the trailing end of the top sheet. 

1. A feeding apparatus for individual feeding of sheet material from a pile in a first, feeding direction, comprising supporting means for the pile, a top abutment placed over the pile, power means for relative reciprocal movement of said supporting means and top abutment means against and away from each other to exert temporarily, a compressive force on and to release the same from the pile in the vertical direction only, pusher means for engaging an edge of the top sheet in the pile, means guiding said pusher means iN a second direction parallel with the plane of the sheets and lateral of said feeding direction, means for biasing the pusher means against the edge of the top sheet, while said compressive force is exerted on the pile and during release therefrom, for exerting thereon a resilient pressure which is insufficient to overcome the friction caused by said compressive force on the pile but sufficient to laterally displace said top sheet when said compressive force on the pile is being released, a feeding device arranged at the side of the pile in level with said top abutment means opposite the pusher means and having means for receiving and gripping said top sheet and for feeding it in the feeding direction after its displacement by the pusher means, and means opposite the pusher means in level with said top sheet for passage of the opposite edge of the top sheet during said displacing of the top sheet and for stopping movement of the sheet immediately below the top sheet.
 2. A feeding apparatus as described in claim 1 wherein said pusher means includes a pusher arm having a surface to rest on the top of the pile, and having behind said surface a step slightly lower than the thickness of a sheet in the pile and a recess between said surface and said step for temporarily receiving the edge of the top sheet as it is lifted by said step.
 3. A feeding apparatus as claimed in claim 1 including stop means closely adjacent the edge of top sheet on the side opposite said pusher and downstream thereof relative to said first, feeding direction for limiting lateral movement of the trailing end of the top sheet. 